McLaren prioritised a revamp of the car before the summer break to add downforce to the car, meaning it didn't have the time to come up with a separate low-drag package.
That made its MCL60 extremely vulnerable on the long straights at Spa-Francorchamps, where Lando Norris and Oscar Piastri were unable to race their rivals.
The team has now moved to avoid a repeat at Monza, where aerodynamic efficiency is even more crucial to be competitive.
Rather than building an all-new Monza package the Woking squad has opted to make significant tweaks to its lower downforce offerings in a bid to provide its drivers with a more raceable car on the straights.
Its main changes are a revised rear wing layout, which has been significantly trimmed to reduce drag and its bottom spoon-shaped part removed.
As noted in its explainer to the FIA, McLaren shipped a "lower drag rear wing assembly with an offloaded mainplane and flap."
That is compounded by a revised flap assembly that gives the team two different trimming options, as well as a modified rear wing endplate. It has also trimmed its rear corner winglets.
On the front of the car, it has reduced its front wing flap to provide aerodynamic balance with its trimmed rear wing.
Source: Autosport